Synthesis and photophysical properties of peripherally and non-peripherally mercaptopyridine substituted metal free, Mg(II) and Al(III) phthalocyanines.

The syntheses and photophysical properties of metallophthalocyanines containing Mg(2+) and Al(3+) as central metal ions and their unmetallated derivative (complexes 3-8) tetra- substituted at the non-peripheral (α) and peripheral (β) positions with 2-mercaptopyridine are reported. The trends in triplet and fluorescence quantum yields are described for these compounds. The complexes exhibited relatively high triplet quantum yields (Φ(T)) ranging from 0.33 to 0.54 and fluorescence quantum yields (Φ(F)) ranging from 0.02 to 0.29. Triplet state lifetimes of the complexes were long ranging from 120 to 460 μs, indicating a potential use of these complexes as photosensitizers.